Spatial relations of slums: size of slum clusters

More than half of the world’s population currently lives in cities. In many parts of the world, slums are part of the urban landscape. Despite different history, cultures and continents, slums share common properties. This allows for abstraction and modelling. In this context, the objective of this paper is, to gain insight into the intraurban pattern of slums. Therefore spatial relations, i.e. the cluster tendency of slums, in Dhaka (Bangladesh) and Rio de Janeiro (Brasil) are analysed on different length scales and compared. It is found that the length scale of the analysis has a huge influence on the form of the spatial relationship. On the city scale slums are clustered, while on smaller scales there is a relatively large variation in spatial relationships with predominantly random distribution. It is observed that there is a scale where the large variations of the spatial relationships vanish in a sharp transition. This scale is interpreted as a characteristic size of slum clusters, which has implications for understanding the emergence of slums and urban modelling.